The EF 24-105mm f/4L IS II USM is a Canon L-series zoom covering wide-angle to short-telephoto focal lengths and featuring a constant f/4 maximum aperture. Version II of this popular lens sports a redeveloped optical design, which includes four aspherical elements to significantly reduce distortion and spherical aberrations throughout the zoom range for great sharpness and accurate subject rendering.  this 24-105mm f/4 also sports a ring-type USM and internal focusing mechanism to enable quick, quiet, and accurate autofocus performance, as well as full-time manual focus override. A four-stop-effective Image Stabilizer is also used to minimize the appearance of camera shakes for sharper handheld shooting. Constant f/4 maximum aperture maintains consistent illumination throughout the zoom range. An Air Sphere Coating has been applied to individual elements to reduce backlit flaring and ghosting for greater contrast and color fidelity in strong lighting conditions. A ring-type Ultrasonic Motor (USM), along with an internal focusing design, optimized focusing algorithms, and a high-speed CPU, is employed to deliver fast, precise, and quiet autofocus performance as well as full-time manual focus override. As a member of the esteemed L-series, this lens has a weather-resistant design that protects against dust and moisture to enable its use in inclement conditions.